1. Field of the Invention
This invention relates to a manually-operated pinch or crimp valve for regulating the flow of a fluid through flexible tubing. More particularly, the valve operator is a two-position device that requires low actuator pressure for stopping or initiating fluid flow, which characteristic is especially useful for handling fluids stored under high pressure.
2. Description of Prior Art
Pinch valves are generally provided to a continuous duct, tube, or other flexible conduit or line to control the flow of fluid through that line. Such valves control or terminate fluid flow by constricting or pinching the line, thus maintaining fluid under pressure within the line and upstream of the valve. While a number of different types of pinch valve designs are known, many of the existing pinch valves in use are either complicated in design and construction with too many component parts or are inefficient in actually maintaining a closed condition. Frequently, prior art pinch valves, when closed, allow leakage past the valve.
Pinch valves have many applications in industry, and a wide variety of valves have been developed to serve different industrial requirements. For some demanding applications requiring high flow rates, high pressures, high temperatures, no contamination, corrosive materials handling or precision metering, such as semiconductor processing, precision instruments, medical, pharmaceuticals, chemical, food processing or the like, existing pinch valve designs are not fully satisfactory.
The limitations of existing pinch valve designs include factors such as: construction materials such as plastics, elastomers, and metals; sliding surfaces which lead to wear, cleaning and sanitation difficulties; and, complex geometry also having accompanying cleaning and sterilization difficulties. Size, and cost limitations are other complicating factors in pinch valve design.
In the past, numerous pinch valve designs have been suggested and such designs have been generically categorized by the nature of the tube compression encountered—whether by roller tube or by perpendicularly reciprocated tube contacting element (a blade) and also by how the blade is operated. Operating schemes have included springs, levers, and screw actuators.
The inventor hereof is also the inventor of U.S. Pat. No. 6,883,773 issued Apr. 26, 2005, which patent describes a pinch valve controlling fluid through flexible tubing. In this valve, an actuator, upon the application of pressure, overcomes the spring bias causing the pinch element to move away from the collapsed flexible tubing and initiate fluid flow therethrough. While this valve was adequate at low fluid pressure, at higher fluid pressures, it was ascertained that the manual pressure at the actuator was unacceptable.
Through the prior patent the inventor hereof became familiar with the following patents, all of which are original classification 251/7 or cross-referenced thereinto:
patentInventorIssue Date48,421Matthews, Jr.June 1865307,871RichtmannNovember 18842,471,623HubbellMay 19493,262,670RussellJuly 19664,634,092Daniell et al.January 19876,536,738Inoue et al.March 2003
In the course of preparation, for the within disclosure several patents and published applications became known to the inventor hereof. The following patents are believed to be relevant and are discussed further as to the significance thereof:
U.S. patentspatentInventorIssue Date4,029,441Fischer, L.Jun. 14, 19774,071,039Goof, S. K. L.Jan. 31, 19784,688,753Tseng, et al.Aug. 25, 19874,895,341Brown et al.Jan. 23, 19904,960,259Sunnanväder et al.Oct. 2, 19905,088,522Rath et al.Feb. 18, 19926,036,166Olson, D.L.Mar. 14, 20006,536,738Inoue et al.Mar. 25, 20036,554,589GrapesApr. 29, 20036,840,492Boyne-AitkenJan. 11, 20056,883,773MattheisApr. 26, 20056,948,696Aanonsen et al.Sep. 27, 2005
U.S. PATENT APPLICATION PUBLICATIONS2005/0258382YangNov. 24, 20052006/0049371OhnishiMar. 9, 20062006/0138369Tomioka et al.Jun. 29, 2006
Several of the above patents have plungers acting upon flexible tubing in various configurations. Goof '039 uses fluid pressure within a control assembly to regulate plunger position and fluid flow. Tseng et al. '753 drives a wedge-shaped tongue member to force the tubing onto a tubing occluding surface, which surface conforms the original bottom half of the tubing. Grapes '589 has a tube tunnel in which to dispose the flexible tubing and lowers a plunger thereagainst. The plunger has a spherical tube contacting end dimensioned to fit the exterior of the tube. None of these operate into a throat of diminishing size. In systems operating under high pressure, such arrangements are not suitable for manual actuation.
In addition to plungers, various means for protecting the flexible tubing that is pinched to cut off fluid flow. Rath et al. '522 teaches a pump hose with arcuate portions to minimize stress at the hose joints. Brown et al. '341, Sunnanväder et al. '259, and Inoue et al. '738 show sleeve-like casings surrounding the flexible tubing for purposes of avoiding injurious activities in operation.
The published patent application to Yang shows a suction hose stop valve having a holder through a central passageway and a swivel cap. Here, when the hose is in the open condition, closure is accomplished by swivelling the cap to fold the hose upon itself. Thereafter the swivel cap is latched to maintain the closed position.
Boyne-Aitken '292 patent is representative of a wide variety of tube clamps and clips typically used for intravenous drips or similar fluid delivery. This patent describes two flexible curved beams forming a threshold to the pinch zone of the clamp. These beams act as a stop or retainer preventing free movement between the open segment and the closed segment of the tube clamp and do not have any pinching function once the clamp is open or closed.
Prior art pinch valves also teach the use of flexible tubing inserts. The pinch valve of Aanonsen et al. '696 has a resiliently flexible valve member which is folded upon itself. A valve operator selectively exerts a lateral force upon the valve member to unfold the insert and operate the valve.
The Ohnishi published patent application utilizes various projections on the inner wall of the flexible tubing to ensure complete closure when pressure is applied to the outside of the tubing. The patterned projections also enable control of microflow through the system.
The present invention provides a novel pinch valve for use with liquids under high pressure. The use of the blade member to force tubing between arc or arc-like segments provides a mechanical advantage over the prior art pinch valves. The use of the arc or arc-like segments, along with its corresponding flexible movement, to open or close the pinch valve and to allow for the flow of the liquids, requires lower hand pressure and less spring action. The arc or arc-like segments overcome the high friction that results from bending the flexible tubing. Such novel design allows for the containment of high pressure liquids when in a closed position, with the ability to open the pinch valve by solely using hand pressure.
While it is difficult to provide a pinch valve design that satisfies all the requirements of industry, there is a need for a normally closed valve or a normally open valve with improved features for demanding applications. For example, it is desirable for such a valve to provide complete shutoff at high pressures and require drgonomically suitable manual operating characteristics.